A key objective for any artist wishing to sustain a lasting career is, of course, to develop a loyal following that will return in their droves tour after tour, album after album.

And nowhere is that ethos better encapsulated than at the heavier end of the music spectrum, where fans stick with their bands with a fervour normally associated with sports teams.

It’s not just some cult concern either. At the top end, the Iron Maiden juggernaut keeps on rolling, ...